Efforts to treat vertebral compression fractures (VCFs) with kyphoplasty or vertebroplasty have fallen flat for some patients. Both of these techniques involve injecting cement into the broken and collapsed vertebral body. But the cement oozes out and damages nearby blood vessels and nerves.
The oozing cement can also form an emboli (clot) that can travel to the heart or brain and make matters much worse. One other problem is that injecting cement into the main body of the vertebral bone creates a rigid bone that is actually too stiff for the weak (osteoporotic) bone. The result can be even more fractures in the vertebrae above and below the cemented level.
But vertebral compression fractures (VCFs) caused by weak, osteoporotic bones can’t be just left to heal on their own. The end result would be further collapse of spine, chest, and abdomen affecting breathing, appetite, and digestion. And since most of the VCFs occur in adults aged 65 or older, there can be additional complications associated with these problems.
Older patients aren’t the only ones affected. Younger patients can experience any of these problems, too. In addition, the implant is expected to be permanent. It doesn’t break down and it isn’t absorbed by the body. This feature could cause problems later for the younger patients.
So what can be done for patients with vertebral compression fractures that can’t be treated locally with surgery? That’s what this study is all about. Medical researchers took five human spines from cadavers (human bodies preserved after death for study purposes), created vertebral compression fractures, and then treated them three different ways. All vertebral bodies from the thoracic spine (T4) to the lumbar spine (down to and including L5) were used.
The first treatment was with kyphoplasty — just the way a patient would be treated with this technique. A deflated balloon was inserted into the collapsed vertebral body. Hydraulic pressure was used to inflate the balloon. The balloon was then collapsed and removed. The empty space left by the inflated balloon was quickly filled in with the injected cement (polymethylmethacrylate or PMMA).
The second treatment was with a titanium mesh implant cemented in place. The implant looks like a diamond-shaped Chinese finger trap with the center expanded out on each side. The collapsed mesh implants are inserted into a channel or pathway drilled into the vertebral body. A special machine is used to expand the device.
The third treatment was with the same titanium mesh implant but without cement. Fluoroscopy, a special 3-D moving X-ray was used to guide implantation in all three treatment methods. Details of surgical treatment and implantation for all three techniques were provided by the authors.
Results were measured by calculating the stiffness of the vertebral bodies and the mechanical load they could withstand. These values were then compared to normal, intact, healthy bone. Subgroups that were compared included males versus females and thoracic (midspine) versus lumbar (low back) vertebral fractures. The outcomes were very interesting.
They found that the best results came when using the titanium cage without cement. The results were most like normal bone with this approach. The kyphoplasty was the least likely to restore strength and stiffness of the bone to normal. No matter what treatment technique was used, nothing returned the vertebral body stiffness back to normal. There were no differences based on sex (males versus females) or type of vertebrae treated (thoracic versus lumbar spine).
The authors concluded that titanium mesh implants may provide a safe and effective alternative to kyphoplasty for the treatment of vertebral body compression fractures. Cement isn’t really needed, so leaving that out can reduce the complications that can occur when the cement oozes out and comes in contact with other body parts.
The results of this study are considered preliminary — too early to make firm recommendations. Further study is needed to test the abilities and limits of titanium mesh implants. At first glance, these devices appear to provide a protective mechanical scaffold when placed inside the vertebral bones. But the long-term effects have not been calculated or compared against kyphoplasty.